The present invention relates to pressure switching devices and more particularly to pressure switching devices of the type used in motor vehicles for sensing the pressure of a fluid and, based upon the sensed pressure, trigger a variety of switching procedures such as illuminating warning lights or the like. Such pressure switching devices find particular application in connection with monitoring oil pressure or brake pressure in a motor vehicle.
Previously known pressure switches have generally included a mechanical control device which is responsive to the pressure of a monitored fluid to execute translatory movement. Using this technology, the mechanical control device occupies a certain position dependent upon the pressure of the monitored fluid and moves in response to pressure changes. As a result of the movement of the controlled device, an electrical contact within the switch is closed at a predefined pressure threshold value. In devices such as this, the pressure threshold value is generally determined by either the tension of a spring in the pressure switch or the position of the contacts within the switch or by a combination of the two. The spring tension acts in a direction opposing the pressure force generated by the monitored fluid. The switching contacts can be disposed in different positions along the translatory movement of the mechanical control device to effect changes in the pressure threshold value.
In addition to the above, mechanical pressure switches are also known to include multiple switching pressure threshold values. In devices such as this, determination of the pressure threshold values are accomplished by providing electrical contacts at multiple predetermined switching positions along the adjustable path of the moveable control device. The electrical contacts are positioned at locations corresponding to the specified switching pressure threshold values.